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-   -   OpenFOAM - Buying a new PC (http://www.cfd-online.com/Forums/hardware/121624-openfoam-buying-new-pc.html)

falstaff August 1, 2013 10:51

OpenFOAM - Buying a new PC
 
Hello Foamers,

I am writing this today as I need a little help in deciding what computer to buy.
I am relatively new to OF and I would like to use it for the following applications:
- importing cad drawings and subsequent meshing of offshore platforms
- Ventilation studies
- Gas dispersion
- Fire modelling

From experience it seems that the number of cells required lies between 2 and 5 millions.

I am not a computer expert by any stretch of the imagination so would like your feedback based on two possible options. Let it be told that I cannot build a machine by myself and my budget is around the £2,000.00 mark.

Option 1)
http://configure.us.dell.com/dellsto...en&s=bsd&cs=04

Option 2)
http://www.meshcomputers.com/Default...omepage_dtbox2

I would greatly appreciate your feedback on these options and any tweaks required to make the most of my simulations.

Thank you for your time

Falstaff

natem August 2, 2013 06:03

Maybe it's just me, but I cannot read your links...

In general I found the following threads quite useful:
http://www.cfd-online.com/Forums/har...-analysis.html
http://www.cfd-online.com/Forums/har...-question.html
http://www.cfd-online.com/Forums/har...rkstation.html
http://www.cfd-online.com/Forums/cfx...dware-cfx.html

I know: OF is neither CFX nor Fluent. If you're aware differences you can still learn from the respective discussions on hardware, though.

Cheers
Nate

falstaff August 2, 2013 08:35

Thanks for the reply and the link which I will read right now.
Sorry about the links, something went wrong. These are the right ones

1) dell
http://configure.us.dell.com/dellsto...en&s=bsd&cs=04

2) meshcomputer.co.uk
http://www.meshcomputers.com/Default...omepage_dtbox2

Thanks


regards
Falstaff

natem August 5, 2013 03:17

Just a couple of comments with regards to the two systems. Be warned that I'm not an expert on this myself (see my recent post in this section of the forum), so this is just based on what I've read and learned in my own research for a new system...

If you're on a restricted budget (and I feel 2k is quite restricted), my general guess is that you will get better value opting for an i7 core rather than for one of the Xeons (good performance, but over-priced). Furthermore you will definitely save if you use "normal" DDR3 RAM rather than ECC (which Dell uses for all its workstations, it seems).
On this basis, it seems to me that the second system would be the better bargain. Having said that, the i7 you selected has only two memory channels.- It might be advantageous using a 2nd generation i7 with four of them. (Remark: It is unclear to me how much exactly OpenFOAM is affected by this bottle neck - see other threads in this issue.)
If you can afford to spend a little more, try getting a six-core processor rather than four cores, from my experience and with the range of mesh sizes you'll be using this will boost OF computation time a lot. You might also try an use faster memory (2133 MHz instead of 1600), but I am not sure if this is actually of use if the processor doesn't support this (actually I've asked exactly this question in my other post - so just keep it in mind).

Sorry I couldn't be more helpful, I hope someone else who is more experienced will help out as well.

Regards
Nate

falstaff August 5, 2013 04:16

Nate,

thanks pal. this is very useful stuff
I think I am going to go ahead with the following
- Intel® Core™ i7 3970X Six Core Extreme Processor (3.50GHz, 15M Cache)
- 32GB DDR3 2400Mhz (4x8GB ) Quad Channel Memory Kit

It comes with a 900W PSU, do you think I should upgrade it to 1.2kW?

Thanks

Regards
Falstaff

natem August 5, 2013 10:15

CPU sounds fine to me.
If you're really going for the 2400 MHz memory, make sure that your motherboard supports this, too! Again, I'd like to highlight one more time that I'm not sure how much use a fast memory is if Intel declares the CPU to be fit for 1600 MHz only (see http://ark.intel.com/de/products/70845). The system is obviously going to work, but to me it's unclear how much you actually gain (if anything). We'd need another user to comment on this here.
As for the PSU I cannot tell. If the system is pre-configured and comes with 900W, I'd think that's fine (and actually it's a hell lot of power, I would have expected something like 600W). However I've been told that quality of PSUs varies a lot and it's definitely worth investing in a good one which provides very stable voltage levels, otherwise you'll see hardware failures more often / earlier over time. I cannot give any advice on which PSUs are considered hiqh quality though.
Good luck!

natem August 6, 2013 07:30

Just wanted to make you aware of this thread (http://www.cfd-online.com/Forums/har...s-cpu-ram.html) where CapSizer explains that faster RAM is only useful if you overclock the memory clock. As far as I know this should be possible with the setup you have in mind. But if overclocking is a no-go to you, you can probably settle for the slower RAM.

Cheers
Nate

falstaff August 6, 2013 07:33

Nate,

thanks a lot once again. For info I have gone ahead with the following workstation:

950W High Efficiency G7 Extreme Modular Super Silent Power Supply

MSI X79A-GD45 Intel® LGA2011 Mainboard - CrossFireX™/SLI™ Support

Intel® Core™ i7 3970X Six Core Extreme Processor (3.50GHz, 15M Cache)

Corsair H80 High Performance CPU Liquid Cooler

32GB DDR3 2400Mhz (4x8GB ) Quad Channel Memory Kit

2GB NVIDIA GEFORCE GTX 680 - 1536 Cores,2 DVI,HDMI,DP - 3D Vision Ready
240GB SSD - Solid State Drive

3TB SATA III 6Gb/s, 7200rpm, 64MB Cache, 8ms Hard Drive


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